1. Field of the Invention
The present invention relates to a display device mounted in a vehicle and particularly to an on-vehicle display device by which a rear seat passenger can watch various videos in the vehicle.
2. Description of the Related Art
FIG. 6 is a schematic view showing a configuration of a related-art on-vehicle display device as to how to dispose the on-vehicle display device in a cabin. The related-art on-vehicle display device allows a person in a rear seat 2 of a vehicle 1 to enjoy watching video with sound from a television set, a Video Tape Recorder (VTR), a Digital Video Disc (DVD), a car navigation system, etc. The on-vehicle display device has a rear seat display 4 installed at a place where a rear seat passenger 3 sitting in the rear seat 2 can watch the video. Video playback systems such as a television tuner, a VTR player, a DVD player and a car navigation system are connected to the rear seat display 4, so that the rear seat passenger 3 can enjoy various kinds of videos and sounds thereon. In addition, in some cases, these video playback systems may be integrally built in the rear seat display 4.
The rear seat display 4 has a storage portion 4a, a rotary portion 4b and a display portion 4c. The storage portion 4a is fixedly attached to a place near the center of the ceiling portion in the cabin. The display portion 4c is attached to the storage portion 4a through the rotary portion 4b so that the display portion 4c can be opened/closed. When not in use, the display portion 4c is rotated manually in the direction of the arrow shown in FIG. 6 so as to be received in the storage portion 4a. The display portion 4c is opened as shown in FIG. 6 only when it is to be used.
Sound accompanying video displayed on the rear seat display 4 is delivered to a speaker in the cabin or to headphones, earphones and the like worn by the rear seat passenger 3. Operation such as selection of kind of video displayed on the rear seat display 4, channel switching of the television set or DVD playback is carried out by a dedicated remote controller, by pressing buttons on an operation panel provided in the rear seat display 4, or by any other means.
As a mode for installing the rear seat display 4, there can be used various modes such as a mode in which the rear seat display 4 is suspended from the ceiling as shown in FIG. 6, a mode in which the rear seat display 4 is imbedded in a headrest of a front seat 5 or in the back of a front seat 5, and a mode in which the rear seat display 4 is mounted on a console box or a floor surface. In each of these modes, the rear seat display 4 is configured so that the rear seat display 4 can be received not to be a hindrance when not in use, and that the rear seat display 4 can be opened only when it is to be used. With such a configuration, a passenger can stretch his or her hand to set the display portion 4c in a position easy to view, and press operation buttons or the like to make operations such as selection of kind of video to be played back, channel switching, angular or positional adjustment of the screen, and sound volume control.
When the rear seat display 4 is attached to the ceiling portion between the front seats 5 and the rear seats 2 in the cabin as shown in FIG. 6, it is necessary to secure the rearward visibility of the driver 6 due to rearward viewing directly or through a room mirror 7, from the point of view of safety. There are however a lot of constraints on height of the ceiling portion in the cabin, size of the display, attachment position of the display, and the like.
Some vehicles are so low in height of the ceiling portion in the cabin that the rearward visibility of the driver 6 cannot be secured when the rear seat display 4 is attached. In such a case, the place of installing the rear seat display 4 may often have to be changed or the attachment of the rear seat display 4 per se may often have to be given up.
When the driver 6 has to confirm safe conditions behind the vehicle 1 by rearward viewing directly or through the room mirror 7 while the vehicle is being driven forward or backward, the rear seat display 4 can be received, rotated or moved manually to secure the rearward visibility of the driver 6. Such operation is however troublesome, and it can hardly be said that the rear seat passenger 3 can enjoy watching the displayed video pleasantly.
Various solutions to the problem have been therefore proposed to positively use the rear seat display 4 for the driver 6 to confirm safe conditions behind the vehicle 1.
For example, JP-A-11-129815 has disclosed a method in which a driver can confirm a rear spot in the dead angle by viewing a camera image displayed on the display in such a posture that the driver looks backward for confirming safe conditions behind the vehicle by eye observation while driving the vehicle backward. The system for confirming safe conditions behind a vehicle has a control portion. When backward driving of the vehicle is detected by a backward driving detection switch, the control portion starts a rearward-looking camera picking up an image behind the vehicle, displays the picked-up image on a display, and makes a display drive portion change the direction of the display surface of the display so that the driver can view the display surface. In this manner, the driver can confirm safe conditions behind the vehicle by eye observation by watching the conditions behind the vehicle with the driver""s face turned backward while driving the vehicle backward. Moreover, the driver can confirm the state of the rear spot in the dead angle by watching the image displayed on the display surface of the display which surface should be ordinarily turned to allow the rear seat passenger to view the display surface.
In addition, JP-A-2-254489 has disclosed a method in which a liquid crystal display is disposed horizontally rotatably in an intermediate portion between front seats and rear seats of a vehicle and in which both video signal switching and display unlocking are performed at the time of driving the vehicle backward so that both the confirmation of safe conditions behind the vehicle and the reception of a television image can be performed by one display. In the on-vehicle liquid crystal display device, a rotary shaft provided in the liquid crystal display is inserted into a fixed base through a plate spring and attached to an E-ring so that the rotary shaft can rotate. A rotary plate is further integrally attached to the rotary shaft so that the rotary plate can rotate together with the rotary shaft. When the driver shifts into reverse gear to drive the vehicle backward, a reverse gear detection signal is output. In response to the reverse gear detection signal, an unlocking unit operates to disconnect an iron core from the rotary plate so that the rotary plate can rotate to a position where the driver can view the liquid crystal display directly. Then, a display position detection switch is turned off and a video changeover switch is turned to the rearward-looking camera side. In this manner, both the confirmation of safe conditions behind the vehicle and the reception of a television image can be performed safely by one display.
On the other hand, there is devised another technique in which a television set attached to the ceiling of a bus vehicle is not provided for the confirmation of safe conditions behind the bus vehicle but can be moved not to be a hindrance to a passenger who wants to move on a passageway in the bus vehicle.
JP-UM-A-1-74682 has disclosed a method in which a television set is attached to a front ceiling on a passageway in a bus vehicle and in which the position of the television set can be moved to a suitable position in accordance with the case where a passenger wants to move on the passageway and the case where a passenger wants to watch television. The television set moving system has a body frame attached between inside and outside panels of the ceiling of the bus vehicle, and a pulley-including movable table movably attached onto the body frame for fixing the television set. Since the driving power of the movable table is transmitted through a wire, the television set moving system can be made light in weight. Moreover, driving due to a motor and driving due to a manual driving unit can be changed over to each other by a clutch. Accordingly, the television set can be moved manually when the motor has trouble.
In the on-vehicle display device described in the related art, there is however fear that the rearward visibility of the driver may be blocked by the rear seat display if a rear seat passenger watches video on the rear seat display disposed in the ceiling portion. Accordingly, the driver cannot confirm safe conditions behind the vehicle sufficiently when the driver wants to confirm safe conditions behind the vehicle through the room mirror while driving the vehicle forward or when the driver wants to confirm safe conditions behind the vehicle directly by eye observation over the rearward area which the driver cannot confirm from the image on the rearward-looking camera while driving the vehicle
In addition, whenever there is a change in the passenger""s sitting state in each seat in the cabin, for example, whenever a passenger sitting in a rear seat moves left or right, whenever the number of passengers is changed or whenever a passenger gets off halfway, a passenger remaining in the cabin has to adjust the position and the direction of the display portion of the rear seat display manually or has to store the display portion of the rear seat display in its storage place. This results in a problem that the operation is troublesome and inconvenient.
The invention was developed to solve the foregoing problems. An object of the invention is to provide an on-vehicle display device which can obtain an optimal display condition in accordance with the current vehicle condition and the passenger""s sitting state and which is prevented from blocking the rearward visibility of a driver.
According to one aspect of the invention, there is provided an on-vehicle display device including: a display unit installed in a cabin of a vehicle for displaying information; a vehicle condition detection unit for detecting a current vehicle condition; a sitting state detection unit for detecting a passenger""s current sitting state in each of seats in the cabin; a rearward visibility detection unit for detecting rearward visibility of a driver; a determination unit for determining an optimal position and an optimal direction of a display portion of the display unit on the basis of the detected vehicle condition, the detected sitting state and the detected rearward visibility; and a drive unit for changing a position and a direction of the display portion of the display unit on the basis of a determination result obtained by the determination unit.
In the on-vehicle display device according to the invention, the vehicle condition detection unit detects the current vehicle condition on the basis of any one item selected from a group consisting of current position of the vehicle, speed of the vehicle, azimuth of the vehicle, driving gear position of the vehicle, brake condition of the vehicle, power-supply on/off condition of the vehicle, and existence of abnormality in the vehicle, or a combination of several items selected from the group.
In the on-vehicle display device according to the invention, the rearward visibility detection unit detects the rearward visibility of the driver due to rearward viewing directly or through a room mirror on the basis of a viewpoint position of the driver and an attachment position and an attachment angle of the room mirror.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion so as to allow a passenger sitting in a rear seat to view display information on the display portion and prevent the display portion from blocking the rearward visibility of the driver through the room mirror, when it is detected that the vehicle is running and the passenger sits in the rear seat.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion so as to allow all passengers sitting in rear seats to view display information on the display portion and prevent the display portion from blocking the rearward visibility of the driver through the room mirror, when it is detected that the vehicle is running and the passengers sit in the rear seats.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion so as to allow a passenger sitting in an assistant driver""s seat to view display information on the display portion and prevent the display portion from blocking the rearward visibility of the driver through the room mirror, when it is detected that the vehicle is running and the passenger sits in the assistant driver""s seat while no passenger sits in any one of rear seats.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion in a condition that the display portion will be received in a predetermined storage place, when it is detected that the vehicle is running and no passenger sits in any one of rear seats and an assistant driver""s seat.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion so as to prevent the display portion from blocking the rearward visibility of the driver due to rearward viewing directly or through the room mirror, when it is detected that the vehicle is being driven backward.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion so as to allow all passengers sitting in the seats in the cabin to view display information on the display portion, when it is detected that the vehicle has been parked or stopped for a predetermined time or longer and the passengers sit in the seats in the cabin.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion in a condition that the display portion will be received in a predetermined storage place, when it is detected that no passenger sits in any one of seats in the cabin.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion in a condition that the display portion will be received in a predetermined storage place, when it is detected that a vehicle power supply has been turned off.
In the on-vehicle display device according to the invention, the determination unit determines the position and the direction of the display portion in a condition that the display portion will be received in a predetermined storage place, when abnormality is detected in the vehicle condition.